The judgment comes from top U.S. military commanders and is supported by recent intelligence community assessments, according to three U.S. officials who work closely on Syrian intelligence matters. At the heart of the concern is that the Syrian military has transferred more and more of its stock of sarin and mustard gas from storage sites to trucks where they are being moved around the country. While U.S. intelligence agencies first saw reports that Syria was moving the weapons last year, the process has accelerated since December, according to these officials. Also worrisome, said two of the officials, is intelligence from late last year that says the Syrian Scientific Research Center—an entity responsible for Syria’s chemical-weapons stockpile—has begun to train irregular militias loyal to Syrian President Bashar al-Assad in how to use the chemical munitions.

The assessment that Syria is moving large amounts of its chemical weapons around the country on trucks means that if Obama wanted to send in U.S. soldiers to secure Syria’s stockpiles, his top generals and intelligence analysts doubt such a mission would have much success, according to the three officials. “We’ve lost track of lots of this stuff,” one U.S. official told The Daily Beast. “We just don’t know where a lot of it is.”

The large-scale movement of weapons, if it is in fact occurring, would violate one of Obama’s earliest declared red lines concerning Syria. Last August he said, “We have been very clear to the Assad regime, but also to other players on the ground, that a red line for us is, we start seeing a whole bunch of weapons moving around or being utilized.”